Mercury MerCruiser Scorpion 350 (330 hp) (2008)
Mercury MerCruiser has done with their 350 Scorpion pretty much what PCM and Indmar have done, with some of their own wrinkles. For example, Mercury MerCruiser has designed its own cylinder head (thanks to Mercury Racing), and the other makers use the “Vortec” head provided by GM. Mercury MerCruiser has also designed an intake manifold and plenum system and proprietary cam shafts which it feels are better than the others.

Mercury MerCruiser is also proud of its “Tunnel Ram” 90 mm throttle body which it says gives instant throttle response. And the Scorpion has other features, such as eliminating fuel return lines for added safety and ceramic-coated exhaust elbows to better resist high temperatures and corrosion. Significantly, the Scorpion operates on 87 octane fuel, and up to 10% ethanol.